1. Field of the Invention
The present invention relates to a hollow, enclosed unit, which may be in the form of a tape, sheet, or the like, which contains foam forming foam agents for being activated to form foam in the enclosure. The enclosed unit may be used in medical applications, as a splint or cast, in industrial applications, for insulating or blanketing purposes, and in numerous other applications where foamed material is desired.
2. Description of the Prior Art
Use of hardenable foam in an enclosure is known. See U.S. Pat. Nos. 3,563,234 and 3,048,169. The invention is concerned with generating the foam within that enclosure.
The present invention is an improvement upon the disclosure appearing in French Publication No. 2,267,082 which was published Nov. 7, 1975. That disclosure concerns a hollow, enclosed tubular tape, comprised of a top and a bottom layer which are edge sealed together to define a flat tape. The enclosure in the tubular tape contains two foam forming agents, one of which is microencapsulated to avoid its reacting with the other agent. The two agents are described as being mixed together, without disclosure as to how they are distributed. Upon activation of the foam forming agents, e.g. by application of pressure externally of the tape to break the microcapsules, the foam forming agents react and form foam in the tube.
The French publication lacks disclosure of appropriate foam forming agents and does not describe an effective manner of supporting both foam forming agents for generating a uniform consistency foam throughout the enclosure of the tubular tape and for precisely controlling the thickness of the foam across the enclosure.
Other characteristics of a foam filled enclosed unit are disclosed in the prior French publication, including various techniques of securing the layers of the enclosed unit together, of defining seals or obstructions at spaced intervals over the unit for helping to confine and prevent shifting of the foam forming agents and of the foam. The heights of these obstructions help define the height or thickness of the foam filled enclosure after the foam is formed.
The present invention is dependent upon effective microencapsulation of at least one of the active ingredients used in forming the foam. Now, microcapsules of liquid materials, such as water, encapsulated in an enclosure material, such as wax, can be distributed over a supporting surface in a uniform manner. See U.S. Pat. No. 3,423,489. Encapsulation technology of the last few years now makes possible the precise controlled distribution of foam forming materials across an entire enclosure.
Use of the invention for forming a splint or cast on a patient's limb is one possibility.
In the usual method of forming a cast or splint about a limb of a patient's body, plaster of Paris-impregnated or coated gauze ribbon is treated with water just prior to application to activate the plaster of Paris for subsequent setting, and then the wet, unset ribbon is wound about the affected limb. Both this method of forming a splint and cast, and the cast itself, have a number of disadvantages, which the present invention is intended to avoid. The step of wetting the gauze ribbon and the gauze ribbon produced are messy and inconvenient to the person wetting the gauze ribbon, the person using the gauze ribbon and the patient to whom it is applied. The setting of wetted plaster of Paris generates considerable heat which can be disturbing to the patient. Also, a plaster of Paris cast or splint is quite heavy. Its removal can be messy and cumbersome. Although newer plastic, fiberglass, or the like splints and casts are lighter in weight and avoid some of the above-described drawbacks, nonetheless, they are still not as light in weight nor as easily applied or removed as a foam-filled enclosure wrapped around the affected limb.
Mixing of an encapsulated substance with another within an enclosure, in a splint or cast forming context, is known, for example, from U.S. Pat. Nos. 3,415,243; 4,060,075; and 4,272,898. But the support and distribution of foam forming agents of the present invention are not disclosed.
Use of the invention for insulating, e.g. a building wall or other enclosed space, is another possibility.
Insulating a structure typically is done with either a viscous liquid foam material which is pumped into a space which is to receive insulation and sets and hardens in place or it is done with thick sheets of preformed insulating material that are applied on the walls or covering around the space. The viscous liquid foam material settles and compresses over time reducing the insulation protection and foam is often comprised of unprotected uncovered material which emits toxic fumes, like formaldehyde. Thick sheet insulation is heavy in weight, and its volume causes it to occupy a large storage space before it is used.